Photographic emulsion containing benzal pyruvic acid derivatives



June 8, 1948. E. P. DAVEY EIAL 2,443,157

PHOTQGRAPHIC EMULSION CONTAINING BENZAL PYRUVIC ACID DERIVATIVES Filed Jan. 9, 1946 4- DIMETHYLAM'INO BENZAL METHOXY- BENZAL l.5.GRAMS PER LITER OF SODIUM SALT OF PYRUVIC ACID DERIVATIVE -BROMO- 4-METHOXYBENZ 4 -DIMETHOXYBENZAL WAVELENGTH SAME AS D+| GRAM PER LIT 4-DIMETHYL- AMINO ER OF BENZAL PYRUVIC ACID mm M RT M H W 5 0 m 7 W L 01 F CJL O A m. w n ma I L B PY m Mm v PE AH 2 RT N .GE MET [MD mm w .d G O B m M? U. ERV A E 5% Wm SLP D MM Amw f SI 5 um n w M .mlfl a 0 w Pa f MM d ,w w w EM 0 5 m m m m 0 w Patented June 8, 1948 PHOTOGRAPHIC EMULSION CONTAINING BENZAL PYBUVIC ACID DERIVATIVES Edward Philip Davey and Edward Bowes Knott, Middlesex, England, assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application January 9, 1946, Serial No. 640,099 In Great Britain February 9, 1945 6 Claims.

This invention relates to photographic materials, especially to sensitive silver salt emulsions and to methods of manufacturing such materials.

It is known to incorporate in photographic layers, substances which absorb some particular waveband of light, for instance, for some purposes a yellow dye is incorporated in a sensitive silver halide emulsion in order to absorb blue light and thereby reduce the gamma of the emu1- sion when exposed to blue light.

For some purposes it is desirable to incorporate in a photographic layer, a substance which absorbs ultra-violet light. To be of general use such a substance must satisfy various requirements. For instance, it is often desirable that it should be water soluble. If it is to be incorporated in a sensitive silver salt emulsion, for instance, a silver bromide, or chloride, or chlorobromide emulsion, it should be such that it has little or no deleterious effect on the emulsion, for instance it should preferably have no effect on the emulsion sensitivity other than to reduce its gamma by absorbing light in the ultra-violet.

We have found that certain derivatives of pyruvic acid are especially useful for this purpose. The benzal pyruvic acids and their salts are especially valuable. Many of these substances absorb highly in the waveband 310 to 350 m but have little or no absorption in the visible light range.

It is, accordingly, an to provide new photographic materials. A further object is to provide new methods for preparing such materials. Other objects will become apparent hereinafter.

In accordance with our invention there is provided a light-sensitive photographic element comprising a light-sensitive layer, said element including a layer containing an ultra-violetlight-absorbing amount of a compound having the formula where, R represents an aryl group and R represents hydrogen or a halogen. Such compounds may advantageously be used in the form of their alkali metal salts, such as the sodium salts, or as their ammonium salts. The preferred compounds are the benzalpyruvic acids which often exist in two forms, one being colourless and the other having a yellowish tinge, and it is the latter form which are of value in the present invention.

object of our invention 2 In a particularly advantageous form of the present invention the compounds of the formula R o J 15 ROH-C -c0on are incorporated in the light-sensitive element with a compound of the type described in copending U. S. Patent 2,403,708, granted July 9, 1946, especially the nitranilines, or with the com pounds described in application Serial No. 646,- 265, filed February '7, 1946, e. g. the nitraniline sulfonic acids.

Substances which can be used in the present invention are given in the following list which gives also the literature references where their preparation is described (the abbreviation J. A. C. S. stands for the Journal of the American Chemistry Society). The position of maximum absorption is indicated in the last column; where the substance stated is known to exist in two forms, it is the coloured form which is here referred to.

Max m 1. Belize] pyruvic acid, J. A. C. S. 1924, 46, 785 300 2. -methylbenzal pyruvic acid, J. A. O. S. 1938, 60, 2469..-. ca. 300 3. 4-bromobenzal pyruvic acid, J. A. O. S. 1940, 62, 25l5 ca. 300 4. ,8-Bromo-4-bromobenza1, pyruvic acid, J. A. C. S. 1940,

62, 2515 310 5. 4.-methoxybenzal pyruvic acid, J. A. O. S. 1926, 48, 2459 330 6. B-Bromo--methoxybenzal pyruvic acid, J. A. G. S. 1926,

48, 2459 335 7. 3-methoxybenzal pyruvic acid, J. A. C. S. 1933, 55, 4643 8. 2-methoxybenzal pyruvic acid, J. A. C. S. 1928, 50, 25 9. 3:4-dimethoxybenzal pyruvic acid, J. A. C. S. 1935, 57, 211. 345 loag-Bromoi-ethoxybenzal pyruvic acid, J. A. G S. 1941 63, 35

0 11. i-dimethylaruinobenzal pyruvic acid 330 Compound No. 11 was prepared as follows: p-dimethylaminobenzaldehyde (14.9 g.) and pyruvic acid (8.8 g.) were mixed at 5 C. and a 12.5% water-methanol (1: 1) solution of potassium hydroxide (40 cc.) added. A yellow colour developed. Methyl alcohol (50 cc.) was added and stirred till the solid had dissolved. After standing overnight the solution was diluted with water and acidified. Orange-yellow plates crystallised.

The effect of adding the above described substances to a gelatino-silver bromide emulsion is illustrated by the examples described with reference to the accompanying drawings showing the gammas obtained at various wavelengths. The emulsion used contained in one litre, 50 grams of gelatin and an amount of silver bromide equivalent to 57 grams of AgNOa. The substances chosen from the above given list were added in aqueous solution and in all cases the finished emulsion was coated at the rate equivalent to 0.5 gram of AgNOs per square foot. The

gamma values given in the drawings were measured in the manner given in Patent 2,403,703.

In Figure 1, curve A is for the emulsion Without any additions. Curve 5 is for that emulsion containing lfi grams per litre of the sodium salt of the substance? numbered 5i'above; 'curvesiefi; H and 9 are likewise for the same emulsion as A but containing the same quantity of the sodium salt of the substances numbered 6, 11 and 9 re spectively.

In Figure 2, curve B is for tlieisame emulsion again as A but containingLOMgram per litre of. p-nitraniline in alcohol (seedatent;240-32108). Curve C is for the same emulsion as B but with the further addition of 1.0 gram per litre ofthe substance numbered 5 above. Curvev D is for the same emulsion as A but containing 1.5 gramsv per litre of l-aminol-nitrobenzene 2 sodium sulphonate (see application Serial No'..'646,'205,-

filed February '7, 1946"), and curve E is for the sameemulsion as-aD buta with the Ifurther addition of -.1.0-gram per litre of the'substance numbered 11 above.

What we claim as ours invention and desire to be secured by Letters Patent of the United States 1 1'. 'A'light-sensitive photographic element: comprising' a support having thereon a silver halide emulsion layer containing an ultra-violet-lightabsorbing amountiof a1benzal pyruvic acid:

2. A light-sensitive photographicelement comprising a support having thereonaisilver halide emulsion layer containing from 1 gram to 1.5 grams per liter ofemulsion" of a 4 -meth0xy benzal pyruvictacidp 3;: A'light-sen'sitivephotographic element comprising a supportfthavingi thereon'ra': silver halide emulsion layer containingfrom' 1'gram'"to"1.5 grams per liter of emulsionofe-bromo-4- methoxy benzal pyruvic' acidi pounds having the formula:

where R represents an aryl group and R is selected'from theclass consisting ofchydrogen and halogen, and-:the alkali metal'and ammonium salts. ofsaid compounds.

6. A light-sensitive photographic element comprising a support having thereon a silver halide emulsion layer containing from 1 gram to 1.5 grams'per liter-of emulsion of the-sodium salt of-a benzal pyruvic acid.

EDWARD PHILIP DAVEY." EDWARD BOWES KNQT'I";

REFERENCES CITED The following references are of record *inthe file of'this patent: g

UNITED STATES" PATENTS Date Number Name 2,241,289 Carroll et ali 'May-'6; 1941 2,4031708 Davey 'et al. July 9;v :1'946 FOREIGN-PATENT 1 Number Country; Date, I

'Great' Britain Aug.- 5,..1940 

